The DynamicPDF Viewer for .NET product has different DLL files for 32-bit and 64-bit CPU architectures. You will need to reference the respective DLL file as per the .NET framework version and platform target (x86 or x64) set to the application. You can refer to the documentation on referencing assembly here.

The DynamicPDF Viewer for .NET product do not have DLL files built for ‘ANY CPU” architecture. Compiling your application for 32-bit platform by referencing the respective 32-bit DLL file will make it work on both 32-bit and 64-bit machines.

I know this is an older post but could I ask how you dynamically loading the DLL at program startup. I know how to determine if the program is running in 32/64 bit but haven't quite figured out the load process. Any help would be great.

There is no option available in DynamicPDF Viewer for .NET product to load the respective DLL file as per the platform target set to the application. You can achieve your requirement using the Assembly Resolve event of your .NET class. You can refer to the documentation on the Assembly Resolve event on the Microsoft website here.